1. Field of the Invention
The present invention relates to a structure and method for mounting a circuit module suitable for electronic equipment, and more particularly, to a structure for enhancing a ground connection of a multi-chip module suitable for electronic equipment, especially to a handheld computer with a slim body.
2. Discussion of the Related Art
Many types of electronic equipment are utilizing IC packages for performing at higher operational speeds and have small and light bodies.
Recently, a multi-chip module (MCM) was used as a package for the coming generation of small and light electrical equipment because the MCM can achieve higher operational speeds and efficiencies for electronic equipment, i.e., a hand-held computer when compared to a single chip module (SCM).
The MCM package includes a wiring board for mounting a plurality of IC chips on it. However, the SCM package includes only one IC chip on the wiring board. The SCM is inferior to the MCM for a signal transmission speed between the IC chip and the wiring boards.
Presently, the MCM is usually mounted on a main circuit board by using a plurality of stacking connectors. Each of the stacking connectors is constructed of a pair of male and female connectors for coupling with each other. Either one of the male connector or the female connector is soldered on a wiring board. The other connector of the pair is soldered on the main circuit board. Thus, the grounding of the MCM and the main circuit board is achieved through a grounding terminal on the stacking connector.
Consequently, one needs to increase the number of grounding terminals for the stacking connectors in order to strengthen the grounding connection or a magnetic shield for the MCM. However, it is difficult to increase the number of grounding terminals since one must change the structure of the stacking connectors.
Further, presently, there are slight variations among the heights of the IC chips in the MCM since the respective IC chips are mounted on the circuit board by coupling the pair of male and female connectors. Thus, the connectors happen to vary slightly in their coupling strengths during the connecting process for the stacking connectors.
The variation among the stacking connectors causes a problem for small-sized electrical equipment, particularly for equipment with a slim body, such as a hand-held computer.
One need for the hand-held computer with the slim body is to install a heat sink for cooling the CPU module made for the MCM. For achieving a sufficient cooling effect, it is important to maintain a particular clearance between the MCM and the heat sink. Since the hand-held computer with the slim body does not have sufficient space for providing many chip devices, the variation among the stacking connectors influences the clearance between the MCM and the heat sink.
If the clearance between the MCM and the heat sink is too much larger than a particular value, a thermal conduction from the MCM is prevented. On the contrary, if the clearance is too much smaller than a particular value, the MCM is pressed against the heat sink. This closeness has bad effects for the operation of the MCM.